43989 has 16 divisors (see below), whose sum is σ = 67584. Its totient is φ = 25200.

The previous prime is 43987. The next prime is 43991. The reversal of 43989 is 98934.

43989 = T₂₂ + T₂₃ + ... + T₆₄.

43989 is nontrivially palindromic in base 2.

It is an interprime number because it is at equal distance from previous prime (43987) and next prime (43991).

It is not a de Polignac number, because 43989 - 2¹ = 43987 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

43989 is an undulating number in base 6.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (43987) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1002 + ... + 1044.

It is an arithmetic number, because the mean of its divisors is an integer number (4224).

2⁴³⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

43989 is a deficient number, since it is larger than the sum of its proper divisors (23595).

43989 is a wasteful number, since it uses less digits than its factorization.

43989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88.

The product of its digits is 7776, while the sum is 33.

The square root of 43989 is about 209.7355477739. The cubic root of 43989 is about 35.3005411511.

Subtracting from 43989 its sum of digits (33), we obtain a triangular number (43956 = T₂₉₆).

Subtracting 43989 from its reverse (98934), we obtain a palindrome (54945).

It can be divided in two parts, 439 and 89, that added together give a triangular number (528 = T₃₂).

The spelling of 43989 in words is "forty-three thousand, nine hundred eighty-nine".